The present invention relates to an apparatus for separating materials by making use of the difference in specific gravities, so that the material to be separated flows against the current of the flowing medium.
In the prior art, the U.S. Pat. No. 2,708,517 introduces a classifier based on the difference in specific gravities, wherein the material to be classified is fed in at the top, and the water employed in the classifier is fed in at the bottom of the apparatus. By aid of the upwards flowing water, the material to be classified is divided into several fractions according to their ability to resist the flowing of the water. Thus the lightest ingredients remain on the water surface and are discharged along with the overflow, whereas the heaviest ingredients sink down onto the bottom of the apparatus. In addition to this, the apparatus gives a possibility to divide the material into a third, intermediate fraction. This is achieved by constructing the apparatus so that the bottom part has an essentially smaller diameter than the top part, and thus the cone surface formed in between causes a difference in the flow rate. The third fraction is discharged from the watersurrounded classification department by employing a discharge pipe. Owing to the several different-sized collecting chambers pertaining to the top, bottom and intermediate fractions, there is formed a plurality of such surfaces onto which the material under classification may accumulate, which from time to time reduces the classification efficiency.
In the apparatus introduced in the U.S. Pat. No. 2,854,136, a mixer is employed for separating samples with different specific gravities from the heaviest impurities contained in the said samples. Therefore there is made a mixture of sand and water, which mixture is then fed into the apparatus according to the U.S. Pat. No. 2,854,136. The impurities thus separated, in the top part of the apparatus, from the samples under treatment, are conducted, along with the sand-and-water mixture, through a perforated intermediate plate into the mixer chamber, wherein the ingredients are separated in accordance with the cyclone principle. In order to improve the separation output, more water is fed into the cyclone separation. Consequently, the apparatus of the U.S. Pat. No. 2,854,136 is very complex in structure and is only suited for separating certain types of materials from each other.
The DE publication of application No. 3 210 972 relates to a separating apparatus, wherein the material to be purified is set into a turbulent flow in successive, serially connected separating chambers. By aid of the turbulent flow the various ingredients with different specific gravities which are contained in the sludge can be separated. Because in the apparatus of the DE publication of application No. 3 210 972, the use of several serially connected chambers is necessary in order to achieve an advantageous separation output, the apparatus naturally takes up a lot of space and is expensive to run.
The purpose of the present invention is to eliminate some of the drawbacks of the prior art and to achieve a new and simpler separating apparatus, which is small in size and economical as for the running expenses, and wherein the separation is carried out on the basis of the difference in specific gravities, so that the material to be separated is fed in countercurrent with respect to the flowing medium employed in the separation process.